JP4433461B2 - Rubber composition and pneumatic tire using the same - Google Patents

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same (hereinafter also simply referred to as “tire”), and more particularly to a rubber composition suitable for use as an inner liner of a tire and a pneumatic tire using the same.

  Generally, an inner liner layer made of a rubber composition containing a low air permeability rubber such as halogenated butyl rubber is provided on the inner surface of a pneumatic tire in order to prevent air leakage and keep the tire air pressure constant. Yes. However, when the content of butyl rubber in the rubber composition is increased, the strength of the unvulcanized rubber is reduced, and rubber breakage and sheet holes are likely to occur.In particular, when the inner liner layer is made thinner, There is a problem that the inner cord is easily exposed during tire manufacture. In addition, when a large amount of carbon black or an inorganic filler with a small aspect ratio is blended with a rubber composition containing butyl rubber such as halogenated butyl rubber, the hardness at low temperature increases and the durability at low temperature deteriorates. At the same time, it is known that workability in the scouring and rolling process is remarkably deteriorated.

  Furthermore, in response to social demands for energy saving in recent years, as a technique for reducing the gauge of the inner liner layer for the purpose of reducing the weight of automobile tires, for example, a plastic film or a blend of a thermoplastic resin and an elastomer is used. There has also been proposed a technique using a film of a composition comprising: However, in this case, although the weight of the tire can be reduced to some extent, the crack resistance and the bending fatigue resistance particularly when used at a low temperature of 5 ° C. or lower are higher than those of the normally used butyl rubber compounding composition layer. Are also inferior, and the tire manufacturing is complicated.

On the other hand, the present inventors have disclosed in Patent Document 1 as a technique that can satisfy both the air permeation resistance and the low temperature durability without causing the above-mentioned problems from a predetermined diene rubber and natural rubber. A rubber composition for an inner liner and a tire including a selected rubber and an organized layered clay mineral are proposed. Patent Document 2 describes a rubber composition in which an organically layered clay mineral is dispersed for the purpose of improving the gas barrier properties of rubber (however, mention is particularly made of application to an inner liner). Patent Document 3 also describes a rubber composition to which an organized clay mineral is applied. Furthermore, Patent Document 4 describes an organoclay complex into which a predetermined quaternary ammonium ion is introduced, which can be used as a thickener or a gelling agent.
JP 2003-306579 A (Claims etc.) JP 2000-80207 A (Claims etc.) US Pat. No. 5,807,629 JP-A-6-287014 (Claims)

  In the above Patent Document 1, the present inventors have provided a high air barrier property by a so-called nanocomposite (composite material) technology using an organically layered clay mineral for a rubber composition mainly composed of diene rubber and natural rubber. It shows that a rubber composition for an inner liner is obtained. However, for butyl rubber, compatibility with dimethyl distearyl ammonium ion-treated clay, which is a general organic clay, is not sufficient as such an organized layered clay mineral. It was difficult.

  Therefore, an object of the present invention is to improve the material used for making a butyl rubber nanocomposite, thereby having low air permeability, excellent properties such as breaking strength and modulus, and good workability. It is in providing a composition and a pneumatic tire using the composition.

  As a result of intensive studies, the present inventor has solved the compatibility problem by using halogenated butyl rubber as butyl rubber and using a predetermined quaternary onium salt as an organically layered clay mineral used for the nanocomposite. As a result, it was found that various characteristics such as air barrier properties and modulus superior to those of the prior art and excellent workability were obtained, and the present invention was completed.

（式中、Ｒ^１は炭素数１〜３０のアルキル基またはベンジル基を示し、Ｒ^２およびＲ^３は（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｎＨ、（ＣＨ_２ＣＨ_２Ｏ）_ｎＨ基または炭素数１〜３０のアルキル基を示し、Ｒ^４は（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｎＨ基または（ＣＨ_２ＣＨ_２Ｏ）_ｎＨ基を示し、ｎは１〜５０の整数を示す）で示される構造を有する４級オニウム塩により有機化されたモンモリロナイトあるいはマイカであって、その含有量が全ゴム成分１００重量部に対し３〜６０重量部の範囲内であり、前記有機化された層状粘土鉱物が、前記４級オニウム塩を２０〜６０重量％の範囲内で含有し、かつ、前記ハロゲン化ブチルゴムがブロモブチルゴムであって、その含有量が全ゴム成分の６０重量％以上であることを特徴とするものである。 That is, the rubber composition of the present invention is a rubber composition containing a halogenated butyl rubber and an organized layered clay mineral, wherein the organized layered clay mineral is represented by the following formula (1),

(In the formula, R ¹ represents an alkyl group having 1 to 30 carbon atoms or a benzyl group, and R ² and R ³ represent (CH ₂ CH (CH ₃ ) O) _n H, (CH ₂ CH ₂ O) _n H groups. Or an alkyl group having 1 to 30 carbon atoms, R ⁴ represents a (CH ₂ CH (CH ₃ ) O) _n H group or a (CH ₂ CH ₂ O) _n H group, and n represents an integer of 1 to 50. Montmorillonite or mica organized with a quaternary onium salt having a structure represented by the formula (1), wherein the content thereof is in the range of 3 to 60 parts by weight with respect to 100 parts by weight of the total rubber component, The layered clay mineral contains the quaternary onium salt in the range of 20 to 60% by weight, and the halogenated butyl rubber is bromobutyl rubber, and the content thereof is 60% by weight or more of the total rubber components. Also characterized by It is.

  The rubber composition of the present invention can be suitably used for a tire inner liner.

  The pneumatic tire of the present invention is characterized by using the rubber composition as an inner liner.

  According to the present invention, as a nanocomposite using butyl rubber having low air permeability, excellent properties such as breaking strength and modulus, and good workability, by adopting the above configuration. It has become possible to realize a rubber composition. Therefore, by using this rubber composition, it is possible to provide a pneumatic tire with excellent filling gas retention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The rubber composition of the present invention is characterized in that it contains a halogenated butyl rubber and a layered clay mineral organized with a predetermined quaternary onium salt.

The specific quaternary onium salt in the present invention specifically includes at least one of a (CH ₂ CH (CH ₃ ) O) _n H group and a (CH ₂ CH ₂ CH ₂ O) _n H group. One quaternary onium salt. By using such a layered clay mineral organized with ammonium ions having an OH group, it becomes possible to improve the compatibility with halogenated butyl rubber, low air permeability, fracture strength, modulus, etc. In addition, it is possible to obtain a rubber composition having excellent workability and good workability.

（式中、Ｒ¹は炭素数１〜３０のアルキル基またはベンジル基を示し、Ｒ²およびＲ³は（（ＣＨ₂ＣＨ（ＣＨ₃）Ｏ）_nＨ、（ＣＨ₂ＣＨ₂ＣＨ₂Ｏ）_nＨ基または炭素数１〜３０のアルキル基を示し、Ｒ⁴は（ＣＨ₂ＣＨ（ＣＨ₃）Ｏ）_nＨ基または（ＣＨ₂ＣＨ₂ＣＨ₂Ｏ）_nＨ基を示し、ｎは１〜５０の整数を示す）で示される構造を有するものを挙げることができる。具体的には、例えば、第四級アンモニウム塩として、ポリオキシプロピレン・トリアルキルアンモニウムクロリド、ポリオキシプロピレン・トリアルキルアンモニウムブロミド、ジ（ポリオキシプロピレン）・ジアルキルアンモニウムクロリド、ジ（ポリオキシプロピレン）・ジアルキルアンモニウムブロミド、トリ（ポリオキシプロピレン）・アルキルアンモニウムクロリド、トリ（ポリオキシプロピレン）・アルキルアンモニウムブロミド等を挙げることができる。かかる４級オニウム塩の詳細は、前記特許文献４に記載されている。 Specifically, as the quaternary onium salt, the following formula (1),

(In the formula, R ¹ represents an alkyl group having 1 to 30 carbon atoms or a benzyl group, and R ² and R ³ represent ((CH ₂ CH (CH ₃ ) O) _n H, (CH ₂ CH ₂ CH ₂ O)). _{n represents an} H group or an alkyl group having 1 to 30 carbon atoms, R ⁴ represents a (CH ₂ CH (CH ₃ ) O) _n H group or a (CH ₂ CH ₂ CH ₂ O) _n H group, and n represents 1 In particular, examples of the quaternary ammonium salt include polyoxypropylene / trialkylammonium chloride and polyoxypropylene / trialkylammonium. Bromide, di (polyoxypropylene) / dialkylammonium chloride, di (polyoxypropylene) / dialkylammonium bromide, tri (polyoxypropylene) / alkylammonium Chloride, tri (polyoxypropylene) alkyl bromide and the like. The details of such a quaternary onium salt is described in the patent document 4.

  Examples of the layered clay mineral include smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, and mica. Montmorillonite and mica, which can be either natural or synthesized. Moreover, these may be used individually by 1 type and may be used in combination of 2 or more type.

  As such a layered clay mineral, it is preferable to use a swellable organic solvent so that the quaternary onium salt molecules can easily enter between the layers of the layered clay mineral (so-called intercalation). By using such a swellable lamellar clay mineral, the quaternary onium salt sufficiently penetrates between the layers, and when kneading with the rubber, further expansion of the layers due to the penetration of the rubber molecules leads to an increase in the rubber matrix. Dispersion of layered clay minerals at the nano-order is obtained. From this point of view, among the layered clay minerals, it is preferable to use mica having a large average particle diameter, particularly swellable mica. The average particle diameter of mica is preferably 3 to 30 μm.

  Organization of the layered clay mineral can be obtained, for example, by immersing the layered clay mineral in an aqueous solution containing quaternary onium ions and then washing the layered clay mineral with water to remove excess quaternary onium ions. By mixing and kneading the organically layered clay mineral thus obtained in a rubber component, the layered clay mineral is dispersed in the rubber as nano-order fine particles, and extremely effectively improves air permeation resistance. It becomes possible.

  The content of the quaternary onium salt in the organized layered clay mineral according to the present invention is preferably in the range of 20 to 60% by weight. Further, as such an organized layered clay mineral, specifically, for example, trade names manufactured by Co-op Chemical Co., Ltd .: Somasif MEE (synthetic mica), manufactured by Southern Clay Products (US), trade names: Cloisite (registered trademark) 30B (montmorillonite) or the like can be used.

  Moreover, although the rubber composition of this invention needs to contain halogenated butyl rubber as a rubber component, it may contain other rubber components. Preferably, the halogenated butyl rubber is contained at 60% by weight or more of the total rubber component. As the halogenated butyl rubber, brominated butyl rubber (bromobutyl rubber) and chlorinated butyl rubber are suitable. For example, commercial products such as Exxon brand name: Bromobutyl 2255, Bayer brand name: Bromobutyl X2 can be used. . In particular, in the case of a combination of a quaternary onium salt represented by the formula (1) and a halogenated butyl rubber, the halogen moiety of the halogenated butyl rubber and OH in ammonium ions that are considered to be relatively compatible with the halogen moiety. It is considered that the effects of the present invention can be obtained better due to the interaction with the group.

  The content of the organized layered clay mineral in the rubber composition of the present invention is preferably in the range of 3 to 60 parts by weight with respect to 100 parts by weight of the total rubber components including the halogenated butyl rubber. If the content is less than 3 parts by weight, the effect of blending the layered clay mineral may not be sufficiently obtained, and if it exceeds 60 parts by weight, the hardness increases and the low-temperature crack resistance decreases. May cause From this point, the more preferable content of the layered clay mineral is in the range of 5 to 50 parts by weight, more preferably 10 to 40 parts by weight.

  Furthermore, in the rubber composition of the present invention, in addition to the above, various chemicals usually used in the rubber industry, for example, fillers such as carbon black, oils, vulcanizing agents, etc. Vulcanization accelerators, antioxidants, scorch inhibitors, zinc white, stearic acid, and the like can be appropriately blended.

  Since the rubber composition of the present invention has excellent air barrier properties, breaking strength, modulus, and the like, it can be suitably applied to tire inner liners. Therefore, in the pneumatic tire of the present invention using this, high filling gas retention can be obtained. Such a tire of the present invention can be produced by a normal production process by extruding the rubber composition as an inner liner member.

  FIG. 1 is a partial cross-sectional view showing a configuration example of a tire according to the present invention. The illustrated tire includes a carcass layer 2 including a carcass ply wound around a bead core 1 and having a cord direction oriented in a radial direction, an inner liner layer 3 disposed on the inner side in the tire radial direction, and a carcass layer 2. Consists of a belt layer 4 having two belts cast on the outer side in the tire radial direction of the crown portion, a tread portion 5 disposed on the upper portion thereof, and sidewall portions 6 disposed on the left and right of the tread portion 5. Has been. Reference numeral 7 denotes a bead filler. In the tire of the present invention, it is only necessary to apply the above-described rubber composition of the present invention to the inner liner layer 3, and the specific structure and material of other members are not particularly limited, and are according to ordinary methods. It can be configured as appropriate. In the tire of the present invention, an inert gas such as air or nitrogen can be used as the filling gas.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by a following example.
Examples 1 and 2 and Comparative Examples 1-6
At the blending ratio shown in Table 1 below (blended so that the pure montmorillonite or pure mica content is 10 parts by weight), it was kneaded at 110 ° C. for 3 minutes 45 seconds using a Brabender manufactured by Toyo Seisakusho, A mixture was obtained. The rubber composition kneaded at 80 ° C. for 1 minute 30 seconds was vulcanized at 160 ° C. using a 0.4 mm mold to obtain an air permeability test sample.

Air permeability (air permeability resistance) test About the vulcanized rubber composition obtained in each Example and Comparative Example, using an air permeability tester M-C1 (manufactured by Toyo Seiki Co., Ltd.) at 60 ° C. Air permeability was measured. The results are shown as an index with the air permeability of Comparative Example 1 as 100. The smaller the index, the smaller the air permeability and the better the air permeation resistance.

  Further, the breaking strength and M300 (measured at 23 ° C. in accordance with JIS K6251-1993) are shown as indexes with the value of Comparative Example 1 being 100. The larger the index, the better the result. Further, the workability was evaluated as follows with respect to roll adhesion and rubber shrinkage.

Calendering was performed with a roll having a roll adhesiveness of 70 ° C., and Comparative Example 1 was evaluated as Δ: normal, while the roll having a large adhesiveness was evaluated as ×: bad, and the one having a small roll was evaluated as good: ○.

Shrinkability of unvulcanized rubber (rubber shrinkage)
The evaluation was based on the shrinkage ratio of the rubber sheet after the roll. The shrinkage rate is measured by taking a rubber heated for 2 minutes in a roll at 70 ° C. into a 1 mm sheet, and measuring the sheet length (X) immediately after that and the sheet length (Y) after 1 hour. Rate = {(X) − (Y)} / (X). The shrinkage rate of Comparative Example 1 was set to normal: Δ, and the shrinkage rate of 10% or less was set to ◯.
These evaluation results are shown in Table 1 below. Details of raw materials in Table 1 are shown in Table 2 below.

  As shown in Table 1 above, in Examples 1 and 2 containing the organized layered clay mineral and halogenated butyl rubber according to the present invention, the air permeation resistance was very good, the breaking strength and the M300 As for each performance of the above, extremely good values are obtained as compared with Comparative Example 1 which does not contain a layered clay mineral. In addition, good results were obtained in both the roll adhesion and the rubber shrinkage rate, which clearly shows that the workability is improved.

  On the other hand, in Comparative Example 2 in which only the amount of carbon black added was increased compared to Comparative Example 1, the air permeation resistance did not change so much and the breaking strength and M300 were improved, but the workability was improved. You can see that it was not done.

  On the other hand, in Comparative Examples 3 and 5 containing the untreated layered clay mineral and the halogenated butyl rubber, the air permeation resistance is improved as compared with Comparative Examples 1 and 2 using only the halogenated butyl rubber. The strength and M300 are lowered and workability is not good. Further, in Comparative Examples 4 and 6 containing a conventional organically layered clay mineral and halogenated butyl rubber, each of the air permeation resistance, breaking strength, and M300 is higher than Comparative Examples 1 and 2 using only butyl rubber. Although the values are improved, it can be seen that the workability is not improved.

It is a fragmentary sectional view showing an example of the pneumatic tire of the present invention.

Explanation of symbols

1 Bead core 2 Carcass layer 3 Inner liner layer 4 Belt layer 5 Tread part 6 Side wall part 7 Bead filler

Claims (3)

A rubber composition containing a halogenated butyl rubber and an organized layered clay mineral, wherein the organized layered clay mineral has the following formula (1):

(In the formula, R ¹ represents an alkyl group having 1 to 30 carbon atoms or a benzyl group, and R ² and R ³ represent (CH ₂ CH (CH ₃ ) O) _n H, (CH ₂ CH ₂ O) _n H groups. Or an alkyl group having 1 to 30 carbon atoms, R ⁴ represents a (CH ₂ CH (CH ₃ ) O) _n H group or a (CH ₂ CH ₂ O) _n H group, and n represents an integer of 1 to 50. Montmorillonite or mica organized with a quaternary onium salt having a structure represented by the formula (1), the content of which is in the range of 3 to 60 parts by weight with respect to 100 parts by weight of the total rubber component,
The organized layered clay mineral contains the quaternary onium salt in a range of 20 to 60% by weight, and
The rubber composition, wherein the halogenated butyl rubber is bromobutyl rubber, and the content thereof is 60% by weight or more of the total rubber components . The rubber composition of claim 1, wherein for use in the innerliner for tire. A pneumatic tire comprising the rubber composition according to claim 2 as an inner liner.

Images